Category Archives: Radio history

US Post Office Airmail Radio System: 1921

1921AprPMA hundred years ago this month, the April 1921 issue of Popular Mechanics described the radio network of the U.S. Post Office Department. At a cost of $26,000, the post office had put together a string of 15 stations–10 owned by the post office, and 5 others shared with other government departments–to facilitate the carrying of airmail across the country.

65 airplanes were in use transporting 200,000 letters daily, and to manage the system and provide meteorological data, radio was necessary. The first one, shown here, was established at College Park, MD. Others were at Bellefonte, PA, St. Louis, MO, Omaha and North Platte, NE, Cheyenne and Rock Springs, WY, Salt Lake City, UT, and Elko and Reno, NV.

Work on the system had begun in 1920, and at press time, sixteen radio men were in the employ of the department. Plans were in the works to equip planes with radio direction finding equipment and radiotelephones.



TV Steeplejacks: 1951

1951AprPMThis gentleman, shown on the cover of the April 1951 issue of Popular Mechanics, is a lot braver than I am, but he was a critical part of the radio-TV industry.

Since TV and FM signals require line of sight propagation, antennas need to be up high, and steeplejacks were the men who made sure they were up there. According to the magazine, some of the employees were old timers used to working jobs up high, but some were young men. There were few accidents, because the one thing all workers had in common was that they could have only one accident.

In New York, the 1250 foot Empire State Building had just grown 222 feet with the installation of the antennas for five New York TV stations. The idea was to eliminate ghosts and extend the range 50 miles.

The magazine pointed out that the building came with a “spike” originally designed as a mooring spot for Transatlantic dirigibles. It came in handy providing a solid base for the antennas.



1961 Speed Mail

1961AprPESixty years ago, the U.S. Post Office tried something that Popular Electronics, in its April 1961 issue, called “Electronic Speed Mail.” The official name for the service was just “Speed Mail,” but it was an early hybrid of electronic mail (or more accurately, facsimile) and snail mail.

The Post Office Department envisioned having centers in 71 cities strategically located across the country. To write a letter that would be delivered the same day, a sender would write the letter on a special form provided by the post office, taking care to write only within the lines. The form was likened to the special “V-Mail” form of World War II, with which letters were microfilmed stateside and delivered to Army Post Offices where they were printed and delivered, or vice versa. In this case, the message form was sealed and deposited into the mails. At the local post office, it was fed in, still sealed, to a facsimile machine. The machine opened the mail, scanned it, and placed it into a sealed container. After the operator was sure that the message had been properly sent, the batch of message forms was destroyed.

The scanned message was then sent via the Echo 1 satellite to the closest post office to the recipient. There, the message was printed and sealed into a window envelope with only the recipient’s address and return address showing. Again, the entire process took place without human eyes seeing the message.

An example of the message blank is shown below. This one bears a message sent from Postmaster General Arthur Summerfield to Vice President Nixon, late in 1960. (Even though the message was sent crosstown in Washington, it was relayed via Chicago to demonstrate the service’s capabilities.)

When the Kennedy Administration took office, newly appointed Postmaster General J. Edward Day (best known for the creation of the ZIP code) was less enamored with the system, and no further efforts were made to promote it. The Western Union Mailgram service (“the impact of a telegram at a fraction of the cost”) was introduced nine years later in 1970, and allowed rapid mail service. Messages were sent by Western Union to the nearest post office, where they were printed and delivered the same day received.



1941 Portable Transmitter-Receiver

1941AprRadioNewsIn the April 1941 issue of Radio News, William D. Hayes, W6MNU, of Oakland, California, recounts that since he liked to build his own equipment and constantly improve as the state of the art progressed, he had amassed a large collection of perfectly good spare parts. To put them to use, he put together this transmitter-receiver. It was intended for portable use while vacationing, but could also be put to use as a backup rig from the home station.

The receiver employed a 27 tube as regenerative detector, with a 47 used for audio output to drive a speaker, mounted on the wooden front panel with a piece of window screen for protection. The receiver covered 70 through 550 meters in two bands. The author noted that tuning the broadcast band was a useful feature, since the set would be used on vacation. He reported that the simple receiver provided very good reception on the broadcast band.

A bandspread capacitor covered the 80 meter ham band perfectly.

The 80 meter transmitter was a crystal oscillator also using a 47 tube. The use of the same tube as used in the receiver was intentional, to minimize the number of spare tubes that had to be carried. With the type 80 rectifier tube, only three spare tubes had to be brought along.

The author reported that from his cabin in the Santa Cruz mountains of California, and with a 130 foot antenna only 10 feet off the ground, he made numerous contacts with California, Washington, Oregon, Idaho and Nevada.

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Aleutian Islands Earthquake and Tsunami: 1946

 

Hilo residents fleeing tsunami. Wikipedia photo.

Hilo residents fleeing tsunami. Wikipedia photo.

Today marks the 75th anniversary of the April 1, 1946, Aleutian Islands earthquake and tsunami.  The quake had a magnitude of 8.6 and resulted in hundreds of casualties, including all five lighthouse keepers at the Scotch Cap Lighthouse on Unimak Island. 55 foot waves raced across the Pacific at 500 miles per hour and hit Hawaii 4.9 hours later. In Hilo, 173 were killed, including some who were swept out to sea by the receding waters. The destruction prompted the creation of the Seismic Sea Wave Warning System, the forerunner of the Pacific Tsunami Warning Center.

As detailed in the August 1946 issue of QST, at Ikatan, Alaska, the quake was felt by amateur radio operator Henry W. Peterson, K7FFG, who reported four earthquakes followed by a tidal wave cresting at 60 feet. His home was washed into the bay and many other buildings were damaged. He reported families having to head for the hills until daybreak when they could see what was going on.

At 6:00 AM, he put out a call of QRR, but was unable to make contact until 10:00 AM, when he got in touch with government station KNLL. He also raised Signal Corps station WXFP, which requested that he keep a constant radio watch and report every 15 minutes for 24 hours. He then reported all shocks twice a day. There were a total of about 70 shocks up through April 7.

Local residents were very relieved to know that he was in contact with the Signal Corps and could get help at any time if needed.



1961 British “Ranger 3” 3-Transistor Regen

1961MarRadioConstructor2Shown here from the March 1961 issue of the British magazine Radio Constructor is a set dubbed the “Ranger 3,” a pocket sized three-transistor receiver for the medium waves, including the 160 meter ham band and marine frequencies. The set employed a regenerative detector and had a built-in ferrite antenna. The basic set used an earphone, but as shown in the schematic, it could drive a speaker with a few additional parts.

As was often the case with this magazine, there was a construction article, and the ad for a parts supplier conveniently appeared in the same issue with all of the parts. In this case, Henry’s Radio Ltd. of London could supply all the required parts for just over 79 shillings.

The ad points out that the set should be able to pull in Radio Luxembourg in most areas, and the ad turns this into “Luxembourg Guaranteed (where normally receivable).” The BBC had a monopoly on broadcasting in Britain, and the English commercial program from Luxembourg was a popular alternative.

This simple set did a good job of pulling in the distant station because it was optimized for the station’s wavelength of 208 meters (1439 kHz). Since this was close to the top of the dial on most sets, the reception might be marginal, since they were probably optimized for the middle of the broadcast band. The Ranger 3, however, covered 600 kHz to 2.5 MHz, meaning that the Luxembourg station was right in the middle of the dial. In fact, the article suggested waiting until late at night to tweak the receiver, using Radio Luxembourg as the test signal.

According to the article, the set was a very good performer, pulling in numerous continental stations, especially at night.

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1961 Two Transistor “Little Cub” Broadcast Set

1961SprRadioTVExpThe young man shown here has been drawing Social Security for a few years now, but in 1960, he was pulling in a broadcast station thanks to the two transistor receiver described in the Spring 1961 issue of Radio TV Experimenter.

The set was dubbed by the magazine as the “Little Cub,” and was described as an ideal project for boys, individually or in groups. The circuitry was mounted on the front panel, which was a printed circuit board. Half the fun of building the set was etching the circuit board using etchant liquid. According to the magazine, contact with clothing would cause it to be soiled with a brownish color, “but this solution is not dangerous in any form.”

The circuit board traces actually went on the front of the board, and additional decorations and dial markings were added, meaning that the lettering was all in copper.

After the circuit board was etched and rinsed, the glass baking pan in which it did its work was washed with soap and water and put away, and Mom was presumably none the wiser. Then, the two transistors and one diode and other components were soldered in place. The first stage, a 2N414A transistor, served as RF amplifier and used feedback to boost the signal. A 2N107 transistor was used as audio amplifier. The set also featured a phono input which could be hooked to a record player.

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1971 Italian One Tube Reflex Radio

1971MarRadiopraticaFifty years ago, this Italian gentleman is expressing his approval at the loudspeaker volume coming from this one-tube medium wave set, described in the March 1961 issue of Radiopratica magazine.

The set used a single dual tube, an ECL86, known in America as a 6GW8. The tube was reflexed to get double duty out of the tube, allowing the use of a speaker with a relatively simple circuit. The set ran off line current, thanks to solid state rectifiers, and the detector is also a solid state diode.

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1951: Building the Family Foxhole

1951MarPS1951MarPS4Seventy years ago this month, the cover of the March 1951 issue of Popular Science featured this artwork by artist Denver Gillen (who made the first drawings of Rudolph the Red Nosed Reindeer, and later, numerous covers for Outdoor Life) showing “what an A-Bomb blast may do to your home,” but with an inset of a family safely hunkered down in their family foxhole.

The cover entreats the buyer to save the issue, since it contains a special section on emergency preparedness written by Michael Amrine, formerly of the Atomic Energy Commission.

The magazine’s editors noted that much of the literature regarding civil defense was “tragic nonsense–aspirin for cancer. Even the official booklets say mainly, ‘Keep calm, keep covered, and follow directions.” But it goes on to say that official directions might not be forthcoming, since there did not exist civil defense organizations comparable with the problem. Instead, the magazine advocated “planning and plain hard work” by individual homeowners, and the magazine contained advice on how to do that. “The hard truth is that the most you can expect from civil defense will be control and rescue work after a bombing. The most effective preparation for atomic attack will be family by family, house by house.”

1951MarPS2The article first noted what not to do, and pointed out that steps such as blacking out the house, taping windows, or even buying a Geiger counter were of very minimal utility. It noted that, as in Hiroshima and Nagasaki, radiation was not going to be the big killer. Instead, it would be the familiar forces of heat and blast, and the article gave pointers on preparing a refuge room to protect against them. The author asked readers to “imagine that your house is in a cyclone or hurricane belt, and next door to a gas tank” and plan accordingly. The most important principles in planning a refuge room were making sure there were at least two exits, keeping out from under heavy furniture or appliances, and preferably being in a corner of the cellar with the least windows or exposure. The importance of using a corner is illustrated by the drawing at left.

After a spot was located, ideas such as shuttering windows and making use of a heavy table or workbench were outlined.

The article included a number of frequently asked questions, including “what should I tell the children?” The answer was simple: the truth. They should be instructed where to go in a raid and how to hit the deck. You shouldn’t scare them, but don’t make it a game, either.

1951MarPS3For homes without a basement, the author suggested placing earth or logs against an outside wall, with a sturdy table inside.

The list of recommended supplies included the usual suspects such as canned food and battery operated lights. Under the category of “valuables,” the recommendation included an extra pair of glasses and a lockbox for valuable papers. Rounding out that category was money (in small bills), on the assumption that, as in the last war, the economy would be in full operation.

The list included a wind-up clock and maps of the city and county. The battery operated radio made its usual appearance on the list. The article noted that utilities would probably be out, although some, especially the gas lines, might continue to function for a time. Since battery operated radios were still quite rare (but not unheard of) in 1951, the article noted that a car radio would also work.

The article did note that it was dealing with just the Hiroshima-style A-bomb, and not the H-bomb. It notes that the H-bomb was then still just a theoretical possibility, but that if perfected, it would wreak the same level of damage over a still larger area.

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1941 “Little Giant” 5 Tube Superhet

1941MarPM1AFor many years, the March issue of Popular Mechanics featured a radio receiver dubbed the “Little Giant,” and the couples here are enjoying the last months of the prewar era by dancing to the sounds of the magazine’s 1941 rendition.

The set is a familiar “All American Five” AC-DC superheterodyne circuit, featuring a tube lineup of 12A8GT, 12K7GT, 12Q7GT, 50L6GT and 35Z4 rectifier.

The magazine noted that the set was easy to build, had unusually good tone, with full volume and distance-getting ability. The cabinet could be homemade, or purchased from a parts house.

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